Skillful hand use is closely related to self-management, employment, leisure activities, and community life. Unfortunately, measures of manual ability have poor psychometric properties and consequently have not been routinely reported by rehabilitation professionals. Most instruments measure only aspects of hand function such as range of motion, strength, and dexterity. Recently developed instruments use a task-oriented approach, but have limited evidence of validity, generalizability, and practicality. The goal of the proposed research is to develop a psychometrically sound and clinically useful instrument that can be used to assess and monitor patients' status and progress in hand therapy. Specific aims are to (1) use Item Response Theory methods in a study of rehabilitation patients to expand, refine, and establish the validity of the Manual Ability Measure (MAM), a self-report instrument that has been pilot tested with patients with hand injuries, and (2) examine the reliability and validity of self-report by comparing patients' and clinicians' ratings. Two field studies will be conducted. In Study I, the MAM items will be refined with a sample of 300 rehabilitation patients representing five impairment groups. In Study II, the effect of clinician observation on self-reported ratings by hand patients will be evaluated. Agreement between patients' and clinicians' ratings will be calculated at the item and ability level. Moderate to high agreement between patients' and clinicians' ratings are expected. Results of this project will enhance the ability to measure, diagnose, and treat hand problems experienced by patients and will help establish the credibility of self-report as an assessment option. The goal of this career research award is to enable the applicant to become an independent investigator by developing expertise in outcome instrument development. A combination of coursework, intensive mentoring, and completion of the proposed research will expand her knowledge in motor learning and measurement theories and applications. The applicant will be supported by strong mentor commitments and clinical and research supports at the sponsoring institution.